Construction methods are known in which prestressed concrete beams are placed at regular intervals along the supports for a suspended slab. The beams have edges which support planar sheets located therebetween and which constitute the formwork for the slab. Unless the support sheets have considerable thickness and/or strength, the beams are located relatively close to each other to prevent sagging of the support sheets when the concrete is poured and to withstand construction point loadings without failure. Centres of more than 600 mm are not recommended. An example of such a known flooring system is illustrated for comparative purposes in FIGS. 1 and 3.
It is also known in the preparation of concrete floors to locate arched formwork between supports. Australian patents 111529, 147246 and 168002 and my Australian petty patent 653697 illustrate known systems. My earlier system is also illustrated for comparative purposes in FIGS. 2, 4 and 5.
It is known to cast elongate reinforced concrete members in moulds or in a continuous or pseudo-continuous fashion. In one method, the reinforcement means is laid out and thereafter a concrete extruder is passed along the length of the reinforcement means to effectively "coat" the reinforcement means and form the elongate reinforced concrete member.
Integral slab and beam construction systems are also known. U.S. Pat. No. 4,685,264 illustrates one such system.